1. Field of the Invention
This invention relates to silicone resin/silicone rubber composite materials for use in various industrial fields including electric and electronic equipment, business machines, automobiles, and precision machines.
2. Prior Art
A number of methods are known in the art for producing shapes having two distinct silicone parts integrated together. Most methods involved separately heat molding distinct silicone compositions and adhesively joining the molded parts into an integral product.
These methods, however, suffer from the problem that adhesive joining of distinct silicone parts is difficult and time consuming and even when possible, the bond is weak, resulting in an integral product having low dimensional accuracy.
In addition to these methods, integral products in which silicone resin is integrated with silicone rubber can also be produced by coating silicone rubber with silicon resin, for example. The coating method is difficult to carry out and finds use only in coating applications. Because of fragility of the silicone resin itself and weak bond between silicone resin and silicon rubber, the resulting products are inadequate for use as composite materials.
An integral product having combined silicones of different hardnesses has been used as a coating on fiber optics. In this proposal, no attention is paid to the bond between distinct silicone parts.
Over the past years, silicone rubber has found a spreading range of applications in electric and electronic equipment, business machines and automobiles because of its recognized reliability in heat resistance, weatherability and electrical characteristics. Currently available composite materials of silicone rubber with thermoplastic or thermosetting hydrocarbon resins, however, do not take full advantage of the characteristics of silicone rubber. There is a need to have an integrally molded silicone resin/silicone rubber material in which silicone resin and silicone rubber are firmly bonded.